English

Classes of graphs with e-positive chromatic symmetric function

Combinatorics 2018-08-13 v1

Abstract

In the mid-1990s, Stanley and Stembridge conjectured that the chromatic symmetric functions of claw-free co-comparability (also called incomparability) graphs were e-positive. The quest for the proof of this conjecture has led to an examination of other, related graph classes. In 2013 Guay-Paquet proved that if unit interval graphs are e-positive, that implies claw-free incomparability graphs are as well. Inspired by this approach, we consider a related case and prove that unit interval graphs whose complement is also a unit interval graph are e-positive. We introduce the concept of strongly ee-positive to denote a graph whose induced subgraphs are all e-positive, and conjecture that a graph is strongly e-positive if and only if it is (claw, net)-free.

Keywords

Cite

@article{arxiv.1808.03391,
  title  = {Classes of graphs with e-positive chromatic symmetric function},
  author = {Angèle M. Foley and Chính T. Hoàng and Owen D. Merkel},
  journal= {arXiv preprint arXiv:1808.03391},
  year   = {2018}
}

Comments

20 pages

R2 v1 2026-06-23T03:29:34.052Z